BRAIN PRODUCES GROWTH HORMONE

The finding could impact on individuals taking hormone supplements

WEDNESDAY, March 29 (HealthDay News) -- The brain's hippocampus

produces its own store of growth hormone, researchers report.

The finding could have implications for athletes taking growth

hormone and metabolic steroids to increase muscle mass and for

menopausal women using estrogen replacement therapy.

"Growth hormone has been associated with growth of muscles and bones,

and the production of it was believed to lie mainly in the pituitary

gland," study co-author Ken S. Kosik, co-director of the Neuroscience

Research Center at the University of California, Santa Barbara, said

in a prepared statement.

"No one had thought too much about what growth hormone might be doing

in the brain. Hormones in the brain may not be obvious compared to

what they are doing in the rest of the body," Kosik said.

The study, published in this week's Proceedings of the National

Academy of Sciences, also found that women produce more growth

hormone than men, that adults produce more than children, and that

hormone production increases in response to estrogen. Differences in

the amount of growth hormone in the brain may affect reasoning and

mood, the scientists said.

The study authors previously found that production of growth hormone

in the hippocampus increases with learning. The new study found that

stress increases production, particularly in males. The effect of

stress in females depends on how much estrogen they have at the time.

"One interesting interpretation of these results is that exposure to

a stressful event increases growth hormone expression in males -- but

the increase in females may be dependent on their levels of estrogen

at the time," study first author Christine P. Donahue, instructor in

the department of neurology at Harvard Medical School, said in a

prepared statement.

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